Removal of copper from aqueous streams using an iron promoted activated alumina

ABSTRACT

Techniques for reduction of copper from aqueous streams using an iron promoted activated alumina are disclosed. An adsorbent media composition that reduces copper levels in an aqueous feed stream includes an iron containing activated alumina. A process for reducing copper levels in an aqueous fluid using an iron promoted activated alumina sorption media includes contacting the aqueous fluid containing a copper contaminant with the iron promoted activated alumina to achieve reductions in copper from the aqueous fluid.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/203,726, filed Mar. 11, 2014, which claims the benefit of priorityunder 35 U.S.C. §119 (e) to U.S. Provisional Patent Application Ser. No.61/777,172, filed Mar. 12, 2013, entitled Removal of Copper From AqueousStreams Using an Iron Promoted Activated Alumina, the entire contents ofeach of which are incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to use of iron promoted activated aluminaas an adsorbent material for the removal of copper from aqueous streams.

BACKGROUND OF THE INVENTION

Copper exists as a contaminant in water streams. Copper in water can bederived from rock weathering and the treatment of algae with coppersalts but the principal source of copper in water is from the corrosionof copper and brass piping and fittings. When copper and copper basedalloys are present and in contact with water, system upsets such as pHexcursions, oxidizing biocides, ammonia, cyanides, hydrogen sulfide andprocess leaks will dissolve copper.

The human health hazards of copper upon ingestion includegastrointestinal distress with short term exposure and liver or kidneydamage upon long term exposure. The US EPA and regulatory agencies inother countries have limited copper levels in both drinking andindustrial waters. The US EPA has set the maximum contaminant level goalfor copper at 1.3 mg/L or 1.3 ppm for drinking water. Individual USstates may set more stringent regulations for copper in drinking water.Industrial and municipal discharge limits on copper are set to protectaquatic wildlife and fish.

Copper can be removed from water by ion exchange, reverse osmosismembranes, electrodialysis and activated carbon filtration andadsorption. Sorption media are known contaminant removal agents.Activated carbons and functionalized aluminas are examples of effectivesorption media used in industrial wastewater treatment. The mechanism ofremoval of metals and other contaminants by sorption media is by bondingof the contaminant to the adsorbent surface as water containing thecontaminant comes in contact with the adsorbent. The chemistry of thesorption media drives its ability to remove specific contaminants.

SUMMARY OF THE INVENTION

Embodiments of the invention include an adsorbent media composition thatremoves copper from water by contacting the water in a feed stream witha solid sorption media compound comprising an iron containing activatedalumina thereby forming a treated stream comprising less copper than thefeed stream.

Embodiments of the invention also include a composition and process forremoving copper from an aqueous fluid using an iron promoted activatedalumina sorption media. The composition is a sorption media containingfrom 0.1 to 20% iron oxide in a processed blend with aluminum oxide toform a solid iron promoted activated alumina.

Further embodiments of the invention include a process that involvescontacting an aqueous fluid containing ppm to ppb levels of coppercontaminant with an iron promoted activated alumina to achieve very highreductions in copper from the aqueous stream.

Unless otherwise specifically stated, the percentages and parts-pernotations are weight percentages and weight fractions, respectively.

DETAILED DESCRIPTION

The feed stream treatable by embodiments of the current invention can beany aqueous stream containing copper from a source such as, but notlimited to, storm water runoff, groundwater remediation sites, miningoperations, a petroleum refinery, municipal wastewater, utilitywastewater and flue gas desulfurization water, a chemical plant, oilproduction, metal treatments, washing operations, and food and beveragemanufacture. Commercial sources of fluid streams, such as a vehicle washstation runoff, are also treatable by the techniques disclosed herein.Further still, natural sources of water, and naturally occurring bodiesof water are also eligible feed streams.

The feed stream typically comprises water and a copper compound. Thecopper compound is typically in a soluble or dissolved state consistingof compounds of either the cuprous, metallic or cupric valence states.The water may contain copper compounds such as, but not limited to,copper nitrate, copper chloride, metallic copper, copper sulfate, copperselenate, cuprous chloride, and copper fluoride. The feed streamtypically comprises, but is not limited to copper at concentrations of10 ppm to 1 ppt as copper on an elemental basis. Most typical is copperat 2 ppm to 10 ppb. The feed stream can also comprise, consist of, orconsist essentially of water and can contain other metal contaminants,dissolved salt ions such as, but not limited to, sulfate, chloride,calcium, magnesium, carbonate, silica, and organic contaminants.

In implementations of the present invention, the adsorbent media isselected from the group consisting of aluminum oxide, activated alumina,iron oxide and iron hydroxide and combinations thereof. Most preferably,the adsorbent media is activated alumina blended with iron oxide andformed into granular particles. The blending of activated alumina andiron oxide occurs in the powdered form with water and heat to providegranular particles of up to, but not limited to 5000 microns in diameterto 7 microns. Further, the aluminum oxide/activated alumina granule ishighly porous and crush resistant When blended with iron oxide, theresulting iron promoted alumina should have but is not limited to, amacroporosity (>750 A) of 0.05 to 0.15 cc/gram and a crush strengthof>30 lbs. The iron content comprises 0.1 to 20%, more typically, 2 to15% as iron oxide.

The aqueous feed stream is contacted with a sufficient quantity of theadsorbent media composition for a sufficient contact time such that thetreated stream exhibits a reduction in copper content of 10 to 100%,typically 70 to 100%. The feed stream to adsorbent contact time can beas low as 1 second to a high of 30 days, more typically, 5 to 125minutes empty bed contact time or 20 to 60 minutes hydraulic retentiontime. Contact times between 30 days and 10 years are also possible. Thecontact between the media and aqueous stream can be achieved by, but isnot limited to, flow-through continuous or batch vessels,fill-hold-drain tank applications or in porous containments that allowwater to seep into and out of the sorbent media. For example, a waterpermeable bag containing the iron promoted activated alumina compositioncan be used to contact copper-containing fluid. Further still, a foammaterial containing, or impregnated with, the iron promoted activatedalumina composition can be used to contact the copper-containing fluid.

The temperature at which the feed stream is contacted with the sorbentcomposition is in the range of 0° C. to 80° C., preferably from about10° C. to 40° C.

Without being limited to any particular theory, it is believed that inthe sorption media, the aluminum oxide and iron oxide sites attract thecopper and the copper becomes bound by covalent and ionic bonding to themedia. The result is the formation of copper oxide complexes on thesurface and throughout the pores of the sorbent. The copper does notdesorb from the media and the media capacity is not quickly exhausted.This results in a sorption media with a high and sustained ability tocontinuously remove targeted copper contaminants

EXAMPLES

The following examples illustrate the effectiveness of the inventiveprocess for removing copper from an aqueous stream.

Example 1

A water consisting of a tap water base from the Solon, Ohio, municipalauthority containing copper at varying levels of 255 ppb to 302 ppb ofdissolved copper, to which selenium (as sodium selenite) and mercury (asmercuric nitrate) were added in the laboratory, was used as the feedstream with the sorption media composition to test copper removal. Thewater quality for this example is detailed in the following Table:

TABLE 1 Feed Stream Water Quality Water Constituent TypicalConcentration Copper 255 to 302 ppb Calcium   34 ppm Magnesium  9.2 ppmSulfate  147 ppm Chloride 19.2 ppm Nitrate 0.69 ppm Orthophosphate 1.46ppm Fluoride  1.6 ppm Barium 17.3 ppb Boron  186 ppb Iron 41.2 ppbManganese 14.4 ppb Silica 0.68 ppm Strontium  148 ppb Selenium  375 ppbMercury  487 ppb pH 7.03 Alkalinity, CaCO₃  452 ppm

In to a 250 ml capped polypropylene bottle, 175 mL of the feed streamwater was added to 155 grams of iron promoted aluminum, Dynocel CS MAR,obtained from Porocel Industries. Many different commercial productionlots of Dynocel CS MAR were used for testing with all containing anominal 8% iron as iron oxide in activated alumina. Tests are numberedbelow using a selection from the lots. After addition of feed streamwater and the sorption media, the bottle was capped and mixed slowly toensure that the media was wetted by the water. At an ambient temperatureof 72° F., the feed stream water and sorption media composition wereleft in contact without stirring for 30 minutes. After 30 minutes, thewater was withdrawn from the sorption media with a syringe and filteredimmediately through a 0.45 μ syringe filter into nitric acid preservedbottles for copper analysis. The filtration step separated any fineparticles of sorption media from the water to ensure that no furtherremoval continued beyond the 30 minute contact time. Copper for the feedstream and the 30 minute sorption media treated water was measured byICP using EPA method 200.7. The results of the tests are shown in Table2.

TABLE 2 Different Iron Copper Content Copper Content Promoted Activatedof Feed of Sorbent Aluminas Containing Stream Water, Treated Water %7-9% Iron Oxide ppb after 30 Minutes Removed 1 255 2.6 98.9 2 302 4.098.7 3 302 2.4 99.2 4 302 10.1 96.7 5 302 3.3 98.9 6 255 2.1 99.2 7 3026.9 97.7 8 302 3.0 99.0 9 302 2.3 99.2

As can be seen from the data in Table 2, the use of an iron promotedactivated alumina sorption media composition in contact with water in a30 minute fill-hold-drain batch treatment application is very effectivein removing copper from the water.

Example 2

A packed bed, flow-through column of 8% iron promoted activated aluminausing the iron promoted activated alumina sorption media, identified as9 in Example 1, was prepared in a 1″ diameter x 36″ long glass column. Afeed stream of Solon municipal tap water containing varying levels ofcopper was pumped up-flow through the column at a water flow rate of19.0 mL/minute. This flow rate provided an empty bed contact time of25.1 minutes. The empty bed volume of the column was 460.9 cm³. 42liters (equivalent to 91.1 bed volumes) of water were treated. Resultsof the flow-through column test are shown in Table 3.

TABLE 3 Bed Volumes Copper Content Copper Content of Iron of Feed ofUntreated Promoted Activated Alumina Stream Water Inlet Feed SorbentTreated Water % Flow Stream, ppb Exiting Column, ppb Removed 4.3 44118.5 95.8% 8.7 441 17.3 96.1% 13.0 441 12.5 97.2% 17.4 441 11.2 97.5%34.7 339 13.2 96.1% 52.1 126 8.5 93.3% 69.4 339 13.9 95.9% 86.8 474 14.896.9% 91.1 317 13.9 95.6%

Thus, in flow-through column applications, the copper is removed by theiron promoted activated alumina sorption media composition to low ppbcopper levels. In both the batch and flow through applications, copperremoval always exceeded 90%. Further, the flow-through column testdemonstrated sustained removal of the copper by the sorption mediacomposition through varied feed stream levels of copper for many bedvolumes treated and is an indication of high capacity of thecomposition.

Example 3

The results shown in Example 1, Table 2, were achieved using variousiron promoted activated alumina sorbents that each contained a nominalcharge of 8% iron oxide that was added to the composition during theformation of the iron promoted aluminum oxide sorbent pellets andgranules. When iron promoted activated aluminas containing other chargesof iron oxide were tested in the copper removal test described inExample 1, removal of copper was found for all iron oxide levels. Theresults of the tests are shown in Table 4.

TABLE 4 Iron Copper Copper Content Promoted Nominal Content of SorbentActivated Iron of Feed Treated Alumina Oxide Stream Water after 30 %Sample Content Water, μg/L minutes, μg/L Removed A  5% 158 Not detected,<10   >95% B  8% 255 2.6   98.9% C 10% 315 Not detected, <10   >95% D14% 158 Not detected, <10   >95%

It should now be apparent that various embodiments of the presentinvention accomplish the object of this invention. Iron promotedactivated alumina compositions can act as an adsorbent media for theremoval of copper in aqueous streams.

It should be appreciated that the present invention is not limited tothe specific embodiments described above, but includes variations,modifications and equivalent embodiments.

1. A method of reducing an amount of copper species present in anaqueous stream comprising contacting the aqueous stream with an ironpromoted activated alumina sorption media.
 2. The method of claim 1,wherein the copper species is dissolved in the aqueous stream at ppm toppb levels.
 3. The method of claim 1, wherein the contacting the aqueousstream with the sorption media includes as least one of (i) flowing theaqueous stream through a bed comprising the sorption media, (ii) soakingthe aqueous stream into the sorption media, and (iii) performing afill-hold-drain batch treatment on the aqueous stream with the sorptionmedia.
 4. The method of claim 1, wherein the aqueous stream is incontact with the sorption media composition for a time from about 1second to about 30 days.
 5. The method of claim 4, wherein the aqueousstream is in contact with the sorption media composition for a time fromabout 1 minute to about 60 minutes.
 6. The method of claim 1, whereinthe aqueous stream is at least one of an industrial, municipal,oilfield, sea water, and ground water source, wherein the aqueous streamcomprises varied amounts of total dissolved solids and copper.
 7. Themethod of claim 1, wherein the copper species includes at least one ofcopper nitrate, copper chloride, metallic copper, copper sulfate, copperselenate, cuprous chloride, and copper fluoride.
 8. The method of claim1, wherein the sorption media includes between about 0.1% and about 20%by weight of iron oxide.
 9. The method of claim 8, wherein the sorptionmedia includes between about 99.9% and about 80% by weight of aluminumoxide.